| This paper is based on the Coordinated Control System (CCS) reconstruction project of a600MW power plant’s boiler-turbine unit. In order to reach the AGC Evaluation of North China net, this power plant replaces the original boiler-turbine coordination control system with another CCS which is based on the boiler following turbine, so as to improve the regulation speed, accuracy of adjustment and the response rate. But at the same time it brings hidden trouble to the safe operation of the unit for this kind of CCS makes the main stream presser fluctuate too much.In terms of coupling characteristics and the actual, feed-forward compensation is put forward to solve the coupling phenomenon through a lot of analysis and research about the power unit CCS and getting good decoupling effect after simulation experiment. At the same time, the theory study and simulation results show that the radiation signal of furnace does better than drum pressure and first stem pressure in reflecting the combustion status. So it’s more suitable to be the heat signal for the boiler-turbine energy balance. In view of the decoupled object, I propose a cascade control system which makes main stream pressure as the main loop regulated variable and makes the furnace radiant energy signal as the inner loop regulated variable.After determining the control scheme, IMC instead of the PID control is put forward to overcoming the characteristics of the large inertia and large delay of the boiler. At the same time, the scheme is made the simulation experiment. The simulation results show that IMC has very good control effect on step disturbance from the main stream pressure and burn rate.After analyzing the factor of influencing the response time and adjust rate, increasing the load rate of change and using the technology of condensate throttling is put forward to speeding up the response time and regulating speed. And the reconstruction scheme has been used in power plant, and gets good effects. |
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